Quick Start - Trigger.dev

The AI Agents and Prompts surface ships as part of the v4.5 release candidate. Install with @trigger.dev/sdk@rc (or pin 4.5.0-rc.0 or later) to use these features — they aren’t yet on the latest stable, and APIs may still change before the 4.5.0 GA. See supported AI SDK versions and the AI chat changelog for details.

These steps assume you already have a Trigger.dev project with the SDK installed and the CLI authenticated — if you don’t, follow Manual setup (or npx trigger.dev@latest init in an existing project) first. You should be able to run pnpm exec trigger dev from your project root before continuing. The chat surface works with Vercel AI SDK v5, v6, or v7; install whichever major you want. On v7, also install @ai-sdk/otel so your model calls are traced (the SDK registers it for you). See compatibility for the full matrix.

Define a chat agent

Use chat.agent from @trigger.dev/sdk/ai to define an agent that handles chat messages. The run function receives ModelMessage[] (already converted from the frontend’s UIMessage[]) — pass them directly to streamText.If you return a StreamTextResult, it’s automatically piped to the frontend.

trigger/chat.ts

import { chat } from "@trigger.dev/sdk/ai";
import { streamText, stepCountIs } from "ai";
import { anthropic } from "@ai-sdk/anthropic";

export const myChat = chat.agent({
  id: "my-chat",
  run: async ({ messages, signal }) => {
    return streamText({
      // Spread chat.toStreamTextOptions() FIRST — it wires up
      // prepareStep (compaction, steering, background injection),
      // the system prompt set via chat.prompt(), and telemetry.
      // Skipping this is the single most common cause of subtle
      // bugs (silent broken compaction, missing steering, etc.).
      ...chat.toStreamTextOptions(),
      model: anthropic("claude-sonnet-4-5"),
      messages,
      abortSignal: signal,
      stopWhen: stepCountIs(15),
    });
  },
});

Always spread chat.toStreamTextOptions() into your streamText call. It wires up the prepareStep callback that drives compaction, mid-turn steering, and background injection — features that silently no-op if the spread is missing. Spread it first so any explicit overrides (e.g. a custom prepareStep) win.

For a custom UIMessage subtype (typed data-* parts, tool map, etc.), define the agent with chat.withUIMessage<...>().agent({...}) instead of chat.agent.

Add two server actions

On your server (e.g. as Next.js server actions), expose two helpers the transport will call: one that creates the chat session, and one that mints a fresh session-scoped access token for refresh.

app/actions.ts

"use server";

import { auth } from "@trigger.dev/sdk";
import { chat } from "@trigger.dev/sdk/ai";

// Creates the Session row + triggers the first run, returns the
// session PAT. Idempotent on (env, chatId) so concurrent calls
// converge to the same session.
export const startChatSession = chat.createStartSessionAction("my-chat");

// Pure mint — fresh session-scoped PAT for an existing session.
// The transport calls this on 401/403 to refresh.
export async function mintChatAccessToken(chatId: string) {
  return auth.createPublicToken({
    scopes: {
      read: { sessions: chatId },
      write: { sessions: chatId },
    },
    expirationTime: "1h",
  });
}

The browser never holds your environment’s secret key — both helpers run on your server, where customer-side authorization (per-user, per-plan, etc.) lives alongside any DB writes you want to pair with session creation.

Use in the frontend

Use the useTriggerChatTransport hook from @trigger.dev/sdk/chat/react to create a memoized transport instance, then pass it to useChat. Wire both server actions into the transport’s accessToken and startSession callbacks.The example below uses the Next.js @/* path alias for imports from @/trigger/chat and @/app/actions. If you’re not using Next.js (or haven’t configured the alias), swap them for relative imports.

app/components/chat.tsx

"use client";

import { useState } from "react";
import { useChat } from "@ai-sdk/react";
import { useTriggerChatTransport } from "@trigger.dev/sdk/chat/react";
import type { myChat } from "@/trigger/chat";
import { mintChatAccessToken, startChatSession } from "@/app/actions";

export function Chat() {
  const transport = useTriggerChatTransport<typeof myChat>({
    task: "my-chat",
    accessToken: ({ chatId }) => mintChatAccessToken(chatId),
    startSession: ({ chatId, clientData }) =>
  startChatSession({ chatId, clientData }),
  });

  const { messages, sendMessage, stop, status } = useChat({ transport });
  const [input, setInput] = useState("");

  return (
    <div>
      {messages.map((m) => (
        <div key={m.id}>
          <strong>{m.role}:</strong>
          {m.parts.map((part, i) =>
            part.type === "text" ? <span key={i}>{part.text}</span> : null
          )}
        </div>
      ))}

      <form
        onSubmit={(e) => {
          e.preventDefault();
          if (input.trim()) {
            sendMessage({ text: input });
            setInput("");
          }
        }}
      >
        <input
          value={input}
          onChange={(e) => setInput(e.target.value)}
          placeholder="Type a message..."
        />
        <button type="submit" disabled={status === "streaming"}>
          Send
        </button>
        {status === "streaming" && (
          <button type="button" onClick={stop}>
            Stop
          </button>
        )}
      </form>
    </div>
  );
}

Next steps

Backend — Lifecycle hooks, persistence, session iterator, raw task primitives
Tools: Declare tools so toModelOutput survives across turns, typed in run()
Frontend — Session management, client data, reconnection
Types — chat.withUIMessage, InferChatUIMessage, and related typing
chat.local — Per-run typed state across hooks, run, tools, subtasks
Sub-agents pattern — Subtask-as-tool, target: "root" streaming, ai.toolExecute helpers
Background injection — chat.inject() and chat.defer() for between-turn work

​Next steps

Next steps